Higher echocardiographic calcium score seen in CVD patients on peritoneal dialysis

Patients undergoing peritoneal dialysis (PD) with cardiovascular disease (CVD) show significantly higher echocardiographic calcium score (ECS) than those without CVD, according to a Singapore study. This indicates a higher vascular calcification burden in the former.

“Although [ECS] was not found to be an independent determinant of CVD in this undersized study, it is a potentially useful tool to quantify vascular calcification in PD patients,” the researchers said.

Overall, 125 patients on PD were assessed in this study. Of these, 54 had CVD and 71 did not. The researchers compared the ECS (range 0‒8) between participants with CVD and those without. CVD patients were older (69 years vs 56 years; p<0.001) and had a higher prevalence of diabetes mellitus (DM; 81.5 percent vs 45.1 percent; p<0.001). [Singapore Med J 2022;doi:10.11622/smedj.2022052]

In addition, those with CVD had lower diastolic blood pressure (DBP; 72 vs 81 mm Hg; p<0.001), lower phosphate (1.6 vs 1.9 mmol/L; p=0.002), albumin (30 vs 32 g/L; p=0.001), parathyroid hormone (34.4 vs 55.8 pmol/L; p=0.002), total cholesterol (4.5 vs 4.9; p=0.047), low-density lipoprotein cholesterol (2.4 vs 2.8 mmol/L; p=0.019), and high-density lipoprotein cholesterol (0.8 vs 1.1 mmol/L; p=0.002).

The ECS turned out to be higher in patients with CVD than in those without (2 vs 1; p=0.001). However, multivariate analysis revealed that only DM and age independently correlated with CVD.

“Age and DM remained strong independent factors associated with CVD,” the researchers said. “Interestingly, these two factors are known to cause both intimal and medial arterial calcification.” [Am J Kidney Dis 2004;43:572-579]

Of note, no significant between-group difference was observed in the prevalence of insulin use (59 percent vs 50 percent; p=0.488).

Malnutrition and CVD

In patients undergoing dialysis, the Kidney Disease: Improving Global Outcomes (KDIGO) guidelines recommend the assessment of valvular calcification by echocardiography to stratify cardiovascular risk. How this should be done, however, is not specified. [Kidney Int Suppl 2009;(113):S1-130]

The current analysis revealed a possible association between malnutrition and CVD. Previous studies reported a strong correlation between high phosphate levels and mortality, but the present study found significantly lower phosphate levels in CVD patients.

“We hypothesize that decreased dietary intake in the CVD group might have led to lower phosphate, parathyroid hormone and cholesterol levels,” the researchers said. [Am J Clin Nutr 2003;77:834-841; JAMA 2004;291:451-459]

Vascular calcification

An earlier study reported the association of vascular stiffness, a predictor of cardiovascular mortality, with vascular calcification. Thus, it came as no surprise that the CVD group in the current study had lower DBP due to the loss of vascular compliance. [Nephrol Dial Transplant 2004;19:1480-1488]

“Clinical practices might affect the development of vascular calcification,” the researchers said. “Indeed, there is emerging evidence suggesting that calcium loading is a major risk factor for cardiovascular mortality in the dialysis population.”

Use of ‘low-calcium’ dialysate must be standard procedure to prevent coronary artery calcification, improve calcium and phosphate balance, and reduce cardiovascular mortality, according to the researchers. [Am J Kidney Dis 1992;20:367-371]

“There are data showing that the use of noncalcium phosphate binders can retard coronary calcification and reduce mortality,” researchers said. [Kidney Int 2002;62:245-252; Kidney Int 2007;71:438-441]

“The ECS, being a semiquantitative tool, could be useful to monitor vascular calcification and its progression,” they added.